Cannot Activate Survey

Althogh there is tree answers for a question when I tried to activate the survey I have got the error message. I have deleted and re-write the question again but nothing has chaged.

What can I do?

Activate survey(657439)
Error
Survey does not pass consistency check
The following problems have been found:
Question qid-515 ("...."): This question has no answers.
The survey cannot be activated until these problems have been resolved.

I too had faced a similar problem.
When I Checked the questions table, there was a row with specified qid, whereas there was no corresponding row in answers table.
I just deleted the row from questions table and that resolved the problem
Hope this helps...